((Stil it would be a great mistake to abandon your work on the perpetual-motion machine " . thirty the following morning, the bacilli, although certainly dead, were placed in an incinerator for good measure. Some of the biologists and academics who at- tended the destruction felt a trace of re- gret. "We said to each other, 'This is kind of sad we have to destroy this,' " Dr. Jim Roth, an assistant dean for in- ternational programs at the school, re- calls. "Especially the cultures we'd had since 1928." Less than two weeks later, Tom Ridge, the director of Homeland Secu- rity; announced at a Washington press conference that investigators had iden- tified the anthrax that had been sent through the mail as belonging to the Ames strain. It now seemed likely that there was an Iowa State connection to the Ames strain, and that the original culture of the Ames isolate was steril- ized and incinerated with the rest of the veterinary school's collection. Jim Roth had wondered about that possibility, and the school had contacted the EB.I. and the Centers for Disease Control before killing the specimens. Both agencies ap- proved the destruction. "They may be having some second thoughts about that, but it's too late now," Roth says. I n its way, the uncertainty about the Iowa State anthrax reflects the larger puzzlement facing federal officials as they have tried to work out the prove- nance of the anthrax that killed Bob 68 THE NEW YORKER, NOVEMBER 12, 2001 . Stevens and at least three others. As in- vestigators try to determine who is be- hind the bioterror, alternating between theories that its source is foreign or domestic, state-sponsored or freelance, Dr. Roth and his colleagues in Iowa have tried to unravel the problem of the origins of the Ames strain What they do know is that it all began with a sick cow, probably some- where in a pasture in the western part of Iowa, probably in 1979. In alllikeli- hood, a farmer encountered his stricken beast after it was already dead, and had not been witness to the sudden fever, the clumsy staggering, the trembling, and, finally, the convulsions that pre- ceded the animal's death. Anthrax seizes and consumes its victims quickly: The farmer might have suspected anthrax, a diagnosis probably confirmed by his veterinarian immediately upon encoun- tering the carcass. In most ways, the beast would have looked good, even healthy, except for the blood streaming from its nostrils, ears, and rectum. The recommended procedure in Iowa, as elsewhere, is not to disturb the carcass of an animal killed by anthrax. Veterinarians almost never perform an autopsy, because opening the beast's body would expose the bacteria to air, triggering the organism's self-preserva- tion mechanism. Bacillus anthracis is a spore-forming bacterium, which is to say that, when faced with an environ- mental challenge, it forms a kind of shell, allowing it, acornlike, to lie dor- mant for years, even decades. When Professor Packer opened that 1928 vial of anthrax at Iowa State, the jellylike medium inside the tube had turned hard and crusty, but the anthrax spores inside were still alive. (Packer had put the anthrax in a fresh medium, sealed it back up, and left instructions for some future Iowa State microbiologist to try to revive it again in 2028.) The stricken Iowa cow had probably contracted anthrax by consuming spores that had settled into the Iowa soil, perhaps after an anthrax outbreak in 1950-52, caused by feeding contami- nated bonemeal to livestock. The spores from those afflicted animals had gone to ground, until they were ingested, probably with a clump of grass, by the cow in 1979. Once inside the warm, moist environment of the cow's diges- tive system, the spores came back to life, releasing their bacteria, which grow at phenomenal rates-each organism replicating itself every fifteen to twenty minutes. As the bacteria grew, they ex- creted a toxin that, in essence, caused the animal's immune system to go into hyperdrive, leading to shock and near- instant death. The veterinarian would have dis- posed of the carcass immediately, either by burning it or, if it could be moved without rupture, by burying it after cov- ering it with quicklime. In either case, before disposal, the vet salvaged a spec- imen from the diseased animal, either cutting off an ear and sealing it in a bag or drawing blood from the cow's jugular. The vet would have sent that specimen to the nearest state veterinary diagnostic center, which in this case was almost certainly the lab at Iowa State's College of Veterinary Medicine. Iowa State microbiologists would have seen under the microscope big, rod-shaped bacteria that turned blue when introduced to an identifYing sub- stance called a Gram stain. Further biochemical tests would have proved positive for anthrax. At that point, a sub- culture would have been grown and sent down the street to the Department of Agriculture's National Veterinary Ser- vices Laboratory for confirmation. The original culture was probably put in a vial, which somehow found its way